European railway project links 35 million people

The "Stuttgart 21" rail project in Germany, together with the new line between Wendlingen and Ulm, is a major ongoing infrastructure project. When complete, it will see a 1,500km railway line help connect 35 million people in five countries, enabling travel from Paris, Strasburg, Munich, Vienna, and connecting Bratislava to Budapest. It will provide enormous economic and ecological benefits, regionally, nationally and internationally, seeing 3 different consortiums use a variety of Sandvik tunneling equipment and software.

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"Stuttgart 21" is the culmination of almost a century of urban development for this historic German city. It will see the redevelopment and refocus of the rail hub, four new stations and a new 57km section of track. However, this is only part of the project, which will also see the construction of a new 60km line between Wendlingen and Ulm, providing a route over the Schwabian Alb.

The new "Stuttgart-Ulm" line will also form a major part of a European high speed network, providing a "Main Line for Europe". The 1,500km railway line will connect a total of 35 million people in five countries facilitating travel between Paris, Strasburg, Munich, Vienna and a connection from Bratislava to Budapest. In the context of the overall European rail network, it is part of the central West-East line, and is another piece of the jigsaw that will play a key part in contributing to Western and Eastern Europe coming together economically, politically and culturally. The rail project will act not just as a boost to general economic recovery, will also encourage investment and generate wide-reaching positive environmental benefits.

Demanding tunneling project

Due to the challenging topography and geology of the area the new route will involve the creation of new tunnels. Responsible for much of this is the contractor, Avesco, which has been commissioned by the three responsible management consortia. They consist of the Albabstieg Tunnel Consortium, the Cannstatt Tunnel S21 Consortium and the Feuerbach Tunnel Consortium. The reason for the tunnels is essentially to provide shorter travel times and offer more direct connections.

Further complicating matters is that compared to the current position of the Stuttgart terminal station, the new main station will be turned around approximately 90 degrees. It will be connected to underground feeder lines, including those coming from Bad Cannstatt and Feuerbach. At Feuerbach a 2,449m long main tunnel is being driven in through the 312m Prague intermediate heading. The complex geometry has meant that a total of four different types of cross-section have to be used, with the excavation being generally up to 88m².

Taking into account the specific topography and geology of the route has necessitated different approaches by Avesco. Some of the tunnel structures have been created using mining construction methods, with rock and stone being excavated from the mountain, meter by meter, using drilling and blasting. The roof section of the tunnel – the upper semi-circular profile – is produced in the first stage of the process, and when complete the lower half is excavated with so-called 'bench and floor' until the complete tunnel profile is produced.

Special technique

In total 63km of tunnels will be excavated, representing a height differential of 500m. In order to do this Avesco has relied heavily on its fleet of 14 Sandvik tunneling jumbos and associated equipment. Sandvik's experience and the impressive performance of the tried and tested equipment, has proved to be especially useful. Furthermore, Sandvik's dry drilling system has proved its worth, being the only technique that could be successfully used at Feuerbach.

It was found that driving with the conventional method, i.e. adding flushing water during the drilling process, would change the anhydride material (anhydrous calcium sulphate) into gypsum, so that the material would swell up. After a series of meetings and site visits by Sandvik technical personnel, the tunneling jumbos were converted to the dry drilling system. This additionally provided a "mobile solution" for the 400 to 600 meter long section which will see 475,000m³ of material being excavated at approximately 80m³ per pull.

Complex problems to overcome

There is a similarly complicated geology in Bad Cannstatt. In this case, the pipe roof method of driving is being used as it increases stability in the driving area, and settlement is reduced thanks to the load being shifted in the longitudinal direction. In the cover drilling process, the pipe roof system, consisting of 31 pipes per roof in 15m lengths, is excavated bit by bit, with a rotary striking motion using both of the Sandvik Jumbo's drill heads. In the area of around 2,000m where the pipe roof is being excavated, approximately 80,000 elements are being installed. To accomplish this, 40 experienced tunnel miners are working here in 2 shifts on the six headings.

The machines being used in this unit of the project include four three-armed electro-hydraulic Sandvik D11 tunneling jumbos, one two-armed electro-hydraulic DD820 jumbo, one Axera D06 and one Commando 121 drill rig. "The Sandvik machines are first class," Says Mechanical Engineer, Arnold Fercher, following a visit to the site. In addition to the pipe roof drilling system mentioned above, approximately 600m of dry drilling will be required using the same method as the Feuerbach tunnel.

Further to the south-west is the Albabstieg consortium site, where the companies Züblin and Max Bögl are hard at work. Their work will see almost 200 tunnel miners, and at peak times 270 employed, as well as nine assorted Sandvik jumbos and drill rigs. These will be used to help overcome some of the 'difficulties' to be found on this part of the 250 million Euro investment in the tunnel shell. Technical Project Manager Matthias Abele, and Mechanical Engineer Eric Lüpfert, have drawn heavily on their know-how and experience to deal with such items as small coverings in places and low-vibration blasting. These have been made necessary by the location of nearby buildings, along with the demanding geology due to Karst phenomena and alternating strata of Jurassic limestone.

Reassurance with iSURE

The machinery being used at Albabstieg includes Sandvik jumbos and drill rigs, which are being used at full efficiency. This is being accomplished as the Sandvik equipment is being operated in conjunction with Sandvik's advanced tunneling software, iSURE. This is an advanced new tunnel management and information analysis software for optimizing drill and blast design. Project costs are kept low, and smooth tunneling progress is guaranteed as iSURE provides specific support for the various stages of drilling and blasting processes.

In order to provide the best results, the smooth interaction between drill design, explosive charge and ignition intervals need to be coordinated. This enables depth of pull, profile and base control, meters drilled, blast vibrations, vibration capacity, tunneling progress and costs to be measured, analyzed, as well as adjusted when necessary. In tunneling projects such as found here, when the focus is on driving quality, an integrated approach has proved to be absolutely vital.

It has not only been Sandvik's advanced equipment and software solutions that have found favor on the project. The excellent work and support provided by Sandvik service engineers and technical support has been noted. Even when faced by unforeseeable geological conditions, Sandvik personnel have proved willing, able and capable of providing whatever it takes to support the equipment and the tunnel excavations. Near Ulm the tunnel being excavated could not be accomplished using a great deal of contact pressure, meaning there was not enough counter pressure for the drilling process. After consulting Sandvik the pressure was reduced by a few bars enabling excavation to be resumed safely, and effectively.

Protecting the environment

Once the shell construction work has been completed, existing railway structures at the Albabstieg and the intermediate heading tunnels in the Lehrer Tal will be dismantled and the site installation areas will be backfilled. This will enable local farmers to resume their work, in unspoiled fields. The environmental part of the project has been given a great deal of thought, and the preservation of the locale was given high priority, with any work being rectified to preserve the unique look and feel of the area.

Sandvik personnel and equipment have also played a key role in maintaining this historic and environmental dimension, receiving nothing but praise for their customer care and the performance of the equipment. This is certainly providing benefits for the environment, the contractors, the consortia, and when complete, Europe as a whole.

Key information on Stuttgart 21:

• Total line length: 57km, of which tunnels and cuttings: 33km

• Number of tunnels and cuttings: 16

The new Wendlingen-Ulm line:

• Total line length: 60km, of which tunnels: 30.4km

• Number of tunnels: 9

Feuerbach main structures:

• Consortium partners: Baresel, Kunz, WALO

• Tunnel using mining techniques: around 2 x 2,449m

• Min. / Max. covering: 10m / 150m

• Driving: Blasting including a dry drilling method

• Total order volume: 187.5 million Euros

Cannstatt main structures:

• Consortium: Hochtief Solution, BeMo Tunneling, w&f Ingenieurbau

• Tunnel using mining techniques: around 2 x 3,507m

• Driving: Blasting including a dry drilling method and a pipe roof method

• Total order volume: 285 million Euros

Albabstieg main structures:

• Consortium: Züblin-Tunnelbau, Max Bögl-Tunnelbau

• Tunnel using mining techniques: 5,864m + 5,875m = 11,739m

• Min. / Max. covering: min. approx. 6m / max. approx. 90m

• Geology: white Jurassic formations, fresh water molasse

• Driving: blasting

• Total order volume: 250 million Euros

Technical data: Sandvik DT821-SC tunneling jumbo

• Tunnel dimensions: 8,420 x 14,210mm

• Cross-section: 12 - 110m2

• Bore diameter: 43 - 64mm

• Drilling length: up to 6,180mm

• Weight: 26,500 – 28,900kg

• Length: 14,930mm

• Width: 3,000mm

• Height: 3,600mm

iSURE software used consists of four modules:

• iSURE Tunnel: includes files for drill and blast design, long hole pattern, tunnel line and project files.

• iSURE Report: provides a round report to improve drilling and process development.

• iSURE Analysis: contains data measured and recorded during drilling for analysis of the rock structure and properties.

• iSURE Bolting: Production of up to 5 bolting fans, management for bolt hole application and direction and fan creation.